Australia playing smart.
The big threat for them is Southee and Boult getting early wickets through swing. See the first hour off and the pitch looks fairly flat. None of the NZ bowlers are like Starc/Johnson who can both look shit but then out of nowhere find that ball that batsman just can't play.
NZ are relying on good line/length, subtle variations, and to a degree the batsman making a mistake or getting impatient.
Both teams are doing what they need to, but the longer the stalemate goes the more it will favour Australia if we can't find a breakthrough.